It is more important to tie the alleged perpetrator to the murder victim in this instance. Connecting the suspect to the victim through physical evidence will prove the murder charge, and proving the murder charge automatically proves the kidnaping, because of the circumstances under which her body was recovered.
The jury is not going to find him guilty of one charge, but not the other. They are inextricably linked.
The prosecution intends to prove the murder,and ask the jury to make the reasonable assumption that he kidnaped her in order to do so. It doesn't matter if he took her from her room or found her wandering on the street. It's still kidnap.
Whether the prosecution is successfully making their case is still very open. (not to mention, how well the defense will parry when it's their turn).
JMO